Calorimetric study as a potential test for choosing treatment of B-cell chronic lymphocytic leukemia

Dose and drug changes in chronic lymphocytic leukemia cell response in vitro: A comparison of standard therapy regimens with two novel cyclin‑dependent kinase inhibitors

Chronic lymphocytic leukemia (CLL) treatment is improving; however, some patients do not respond to therapy. Due to the high heterogeneity in disease development, there is an urgent need for personalization of therapy. In the present study, the response of leukemic mononuclear cells to anticancer drugs used for CLL treatment (cladribine + mafosfamide; CM or CM combined with rituximab; RCM) was compared with the response to new cyclin-dependent kinase (CDK) inhibitors: BP14 and BP30. Viable apoptotic and necrotic cells were quantified by flow cytometry using propidium iodide and Yo-Pro stains. CDK inhibitors were studied in several doses to determine the reduction of necrosis and simultaneous increase of apoptosis in leukemic cell incubations with anticancer agents. The distinct cell response to applied doses/anticancer agents was observed. Results obtained in the current manuscript confirmed that modulation of doses is important. This was particularly indicated in results obtained at 24 h of cells incubation with anticancer agent. While an important time for analysis of anticancer response efficacy (monitoring of apoptosis induction potential) seems to be 48 h of cells exposition to anticancer agents. High variability in response to the drugs revealed that both the nature and the dose of the anticancer agents could be important in the final effect of the therapy. The present findings support the thesis that personalized medicine, before drug administration in the clinic, could be important to avoid the application of ineffective therapy.

Relationship between in vitro drug sensitivity and clinical response of patients to treatment in chronic lymphocytic leukemia

To improve the efficacy of therapeutic options in chronic lymphocytic leukemia (CLL) an in vitro system to determine the response of mononuclear blood cells from blood of patients was elaborated. The study combines four approaches, i.e., cell viability, apoptosis rate, differential scanning calorimetry (DSC), and immunoblotting to develop personalized therapy protocols based on the cell sensitivity to drug exposure of individual CLL patients. The complementary analyses were performed on 28 peripheral blood samples from previously untreated CLL patients before therapy. The induction and progress of apoptosis in CLL cells exposed in vitro to purine analogs combined with mafosfamide, i.e., cladribine + mafosfamide (CM) and fludarabine + mafosfamide (FM) were assessed using the above approaches. The changes in thermal profiles (decrease/loss of transition at 95±5˚C) coincided with an accumulation of apoptotic cells, a decrease in the number of viable cells, and differences in the expression of the apoptosis‑related protein PARP‑1. No significant changes were observed in the thermal profiles of nuclei isolated from CLL cells resistant to the treatment. The complementary assays revealed a strong relationship between both the in vitro sensitivity of leukemia cells to drugs and the clinical response of the patients, determined usually after the sixth course of treatment (after ~6 months of therapy). As a summary of studies followed by complementary tests, our findings demonstrate the value of in vitro exposure of CLL cell samples to drugs intended to treat CLL patients, before their administration in order to recommend the most suitable and effective therapy for individual patients.

In vivo and ex vivo responses of CLL cells to purine analogs combined with alkylating agent

BACKGROUND

The heterogeneity of chronic lymphocytic leukemia (CLL) is thought to be due to differences in the expression of factors that regulate apoptosis and cell cycle, giving rise to diverse apoptotic disturbances and tumor properties. Therefore, the primary goal in CLL treatment is to overcome resistance to apoptosis and efficiently trigger this process in leukemic cells.

METHODS

Mononuclear cells were obtained from the blood of CLL patients by Histopaque-1077 sedimentation. CLL cell samples from the blood of drug treated patients, (cladribine or fludarabine with cyclophosphamide; CC or FC), as well as the cell samples of untreated patients exposed to the used drug combinations (CM, FM) or mafosfamide alone for 48 h were fractionated into nuclear and cytoplasmic fractions or were lysed. DNA fragmentation was evaluated by agarose electrophoresis and also cytometrically as sub-G1 population. The expression of apoptosis related proteins and H1.2 histone translocation were evaluated in lysates and nuclear and cytoplasmic fractions, respectively with appropriate antibodies.

RESULTS

Cladribine (C) and fludarabine (F) combined with cyclophosphamide/mafosfamide in vivo, as well as ex vivo trigger apoptosis in CLL cells. These drug combinations (CC; FC/CM; FM) induce leukemic cell apoptosis confirmed by DNA fragmentation, sub-G1 cell number, down-regulation of anti-apoptotic proteins (Mcl-1, Bcl-2), and H1.2 histone translocation in comparison with appropriate control cells, however, to a different degree.

CONCLUSIONS

The kinetics and rate of drug-induced apoptosis in leukemic cells under ex vivo experiments differ between patients, mirroring the differences noticed during in vivo treatment. Individual model cell samples indicate comparable susceptibility to the used drug combinations under in vivo and ex vivo conditions.

Toward personalized therapy for chronic lymphocytic leukemia: DSC and cDNA microarray assessment of two cases

The differences in clinical course of chronic lymphocytic leukemia could have an impact on variations in a patient's response to therapy. Our published results revealed that thermal transition (95 ± 5°C) in differential scanning calorimetry profiles appear to be characteristic for the advanced stage of CLL. Moreover, a decrease/loss of this transition in nuclei from leukemic cells exposed to drugs ex vivo could indicate their diverse efficacy. It seems that the lack of changes in thermal profile could predict patient's drug resistance. In this study, we demonstrate the results obtained after drug treatment of leukemic cells by calorimetry, apoptosis-related parameters involved in expression of genes using cDNA microarray and western blot. These data were compared with the patients' clinical parameters before and after RCC therapy (rituximab + cladribine + cyclophosphamide). The complementary analysis of studied cases with opposite clinical response (CR or NR) revealed a strong relationship between clinical data, differences in thermal scans and apoptosis-related gene expression. We quantified expression of eight of apoptosis-related 89 genes, i.e., NOXA, PUMA, APAF1, ESRRBL1, CASP3, BCL2, BCL2A1 and MCL1. Particular differences in NOXA and BCL2 expression were revealed. NOXA expression in cells of patients who achieved a complete response to RCC therapy was 0.44 times higher in comparison to control ones. Interestingly, in the case of patients who did not respond to immunotherapy, NOXA expression was highly downregulated (RQ = 4.39) as compared with untreated cells. These results were confirmed by distinct cell viability, protein expression as well as by differences in calorimetry profiles.

Can ex vivo evaluation (testing) predict the sensitivity of CLL cells to therapy with purine analogs in conjunction with an alkylating agent? A comparison of in vivo and ex vivo responses to treatment

Malfunctions in the regulation of apoptosis cause the accumulation of malignant, long-lived B CD19+/CD5+ cells in chronic lymphocytic leukemia (CLL). The primary goal in CLL therapy is to overcome resistance to apoptosis and efficiently trigger programmed cell death in leukemic cells. This study demonstrated that the in vivo responses of malignant cells from CLL patients after administration of purine analogs (cladribine/fludarabine) with cyclophosphamide vary significantly. For comparative purposes, the sensitivity of leukemic cells obtained from the same CLL patients to conventional purine analogs and the selective CDK inhibitor R-roscovitine (ROSC) was determined, with and without the addition of an alkylating agent, prior to the onset of in vivo therapy. The kinetics and rate of spontaneous and drug-induced apoptosis of CLL cells under ex vivo conditions differed significantly between patients, mirroring the variability observed during in vivo treatment. Interestingly, individual patients' leukemic cells were comparably sensitive to the drugs under both conditions. Of the drugs examined, ROSC exerted the highest therapeutic efficacy under ex vivo conditions. Our results indicate that ex vivo testing might be useful for identifying the most potent first-line therapeutic regimen for specific CLL patients and possibly for the design of therapies tailored for individual CLL patients.

Microcalorimetry of blood serum proteome: a modified interaction network in the multiple myeloma case

Hereby we report on a novel approach in the study of multiple myeloma (MM), namely, differential scanning calorimetry (DSC) combined with serum protein electrophoresis. Distinct thermodynamic signatures describe the DSC thermograms of MM blood sera, in contrast to the unique profile found for healthy individuals. The thermal behavior of MM sera reflects a complex interplay between the serum concentration and isotype of the M protein and of albumin, and modified ligand- and/or protein-protein interactions, resulting in stabilization of globulins and at least a fraction of albumin. In all MM cases the 85 °C, transferrin-assigned transition is missing. A distinct feature of IgG isotype (κ and λ) DSC profiles only is the presence of a transition at 82 °C. A DSC-based classification of MM depicts two sets of melting patterns (MMt2 and MMt3 with two or three successive thermal transitions), and subsets within each set (MMt2(i) or MMt3(i), the subscript i = 1, 2 or 3 denotes the main transition being one of the three transitions). The results demonstrate the potential of DSC to monitor MM-related modifications of the serum proteome, even at low M protein concentrations, Bence Jones and importantly nonsecretory multiple myeloma cases, and prove DSC as a versatile tool for oncohematology.